A federal judge has ruled the state is discriminating against potentially thousands of U.S. citizens who live in Florida, by charging them higher out-of-state tuition as non-resident students simply because their parents may lack legal U.S. residency.

U.S. District Judge K. Michael Moore found Tuesday that Florida’s rule classifying such students according to their parents’ undocumented immigration status violates the Constitution’s equal protection provision.

“By virtue of their classification, [these Florida students] are denied a benefit in the form of significantly lower tuition rates to the state’s public post-secondary educational institutions,” the judge found in a 19-page opinion that was highly critical of the state’s policy.

“This creates an additional obstacle for [them] to attain post-secondary education from one of the state’s public institutions that is not faced by other residents.”

Moore, who was nominated by President George H.W. Bush and confirmed in 1992, further found the policy “does not advance any legitimate state interest, much less the state’s important interest in furthering educational opportunities for its own residents.”

The state’s Department of Education said it has received the judge’s ruling and is reviewing it.

The Florida students’ lawsuit was filed in October 2011 by the Southern Poverty Law Center. The center represents students who are U.S. citizens and Florida residents, including several from Miami, but whose parents cannot prove legal immigration status.

Florida’s policy is the result of administrative rules created in 2005. Though state law deals with tuition residency issues, it delegates the responsibility to draw up specific rules to the Department of Education (for community colleges) and the Board of Governors (for state universities).

The Southern Poverty Law Center estimated hundreds or thousands of Florida students could be affected by the judge’s ruling. As the policy stands, students who are classified as “non-residents” in Florida can be charged more than triple the cost of in-state tuition. The policy affects those under age 24 and who are claimed as dependents by parents.

The center, based in Montgomery, Ala., hailed the judge’s decision.

“Today is a great day for these young people across the state of Florida who simply wanted the opportunity to get an education and, with that, a chance for the American Dream,” said the center’s deputy legal director, Jerri Katzerman.

“This policy, which was blatantly unconstitutional, will no longer be a roadblock for these young students who may very well be the state’s leaders of tomorrow.”

“Every year Florida graduates thousands of students, many of whom face an uncertain future due to legal restrictions or insurmountable financial burdens because of their immigration status,” Miami-Dade Schools Superintendant Alberto Carvalho said Tuesday.

“Today’s ruling represents a return to reason and the opening of the door of opportunity for deserving students who want nothing more than to give back to the only community and nation that they have ever known.”

In the case of Wendy Ruiz, who was born and raised in Miami, the state’s policy has created a financial hardship for the U.S. citizen. In the eyes of Florida’s higher education system, she’s a dependent student whose parents are undocumented immigrants — and not considered legal Florida residents.

As such, Ruiz, the lead plaintiff in the case, has been charged higher-priced out-of-state tuition at Miami Dade College — even though she has a Florida birth certificate, Florida driver’s license and is a registered Florida voter. One semester of in-state tuition at Miami Dade College costs about $1,200, while out-of-state students pay roughly $4,500.

Ruiz must work multiple part-time jobs just to pay for one class. Other similarly affected students have completely given up on college.

She was unavailable for comment. But in an interview last year with the Miami Herald at the time the suit was filed, she said: “As an American, and a lifelong Florida resident, I deserve the same opportunities.”

Said State Rep. Reggie Fulwood, D-Jacksonville, who had filed a bill to help students like Ruiz: “I hope today’s ruling quickly ends Florida’s ridiculous policy of requiring U.S. citizens to pay expensive out-of-state tuition rates simply because their parents’ legal status. The Republican-controlled Florida Legislature has refused to dismantle this glaring inequity in college admissions policy.”

Cheryl Little, executive director of the Americans for Immigrant Justice, called Tuesday’s ruling a “huge victory” that means more smart, ambitious students can access a college education without paying high tuition.

“I remember when I first learned that kids who were U.S. citizens had to pay outrageous tuition fees simply because their parents were undocumented,” Little said. “I couldn’t believe it. It’s so un-American. This terrible wrong has been fixed.”

The ruling gives immigration advocates another victory. Earlier this year, the Obama Administration decided to allow students who came to the U.S. as children a chance to seek deferred action on their immigration status.

“It’s another step in the right direction. Undoubtedly the real solution to problems like this would be passage of the DREAM Act,” Little said.

The DREAM Act remains a hot-button political issue. Advocates for a stricter, hard-line immigration policy say passage would reward those who entered the country illegally.

Unlike those who would benefit from the DREAM Act, the issue for students like Ruiz is radically different because they are, in fact, U.S. citizens.

Moore, the judge, repeatedly noted that point in his ruling. He also said the state’s rationale for the policy — limited financial means and the quality of public post-secondary education — was “simply incorrect.”

The state’s attorneys argued: “If Florida were required to extend the benefit of in-state tuition rates to all United States citizens regardless of their state of residency, the annual impact would be approximately $200,000,000 in reduced tuition.”

But Moore said the state’s claim was based on its “flawed interpretation” of the 1996 federal welfare reform law. The state’s lawyers argued that “by offering in-state tuition rates to the U.S. citizens of undocumented immigrants, the state would be forced to offer in-state tuition rates to all U.S. citizens.”

The judge, however, said the welfare law is “inapplicable” because the Florida students who sued the state “are not ‘aliens’ but rather U.S. citizens.”